Saw sharpening machine



Nov. 24, 194 2. A. w. KNUTSON 2,302,960

SAW SHARPENING MACHINE Filed Nov. 12, 1940 3 Sheets-Sheet 1 A W K/VUS 0N linventor attorney Nov. 24, 1942. A. w. KNUTSON ,30 ,96

SAW snmrrmme mcumn Filed Nov. 12, 1940 SSheets-Sheet s VV. K N U 76 UN l'mngntor (Ittomg Patented Nov. 24, 1942 UNETE' SAW SHARPENING MACHINE Alfred William Knutson, Geneseo, Ill., assignor of one-half to Frank H. Brown and one-half to Edna Knutson Whited, both of Geneseo,

Ill.

Application November 12, 1940, Serial No. 365,333

6 Claims.

The present invention relates to a saw filing mechanism and more particularly to semi-automatic mechanism of the class indicated. So far as I am aware, all mechanisms of this class heretofore placed upon the market have been large, cumbersome, and expensive, and most of them have not produced wholly satisfactory results. Among the objects, therefore, of my invention are the provision of a saw filing mechanism which can be sold at a price within the reach of all who need a mechanism of this character; the provision of a mechanism of the class indicated which will insure the cutting of all the saw teeth of substantially uniform dimensions; the provision of a combined saw-setter and saw-filer so that a person who purchases one implement is saved the necessity and expense of purchasing a second one; the provision of a combination instrumentality serving for both purposes; the provision of an implement of the character indicated which will shift the saw the proper amount and hold it in shifted position during the filing operation so that the teeth will be cut to a uniform depth and size; the provision of an implement of the character indicated which is not unduly complex and which can therefore be readily set up and adjusted for work by a mechanic ordinarily using such an implement; and such further objects, advantages, and capabilities as will hereafter appear and as are inherent in the construction herein disclosed. My invention further resides in the combination, construction, and arrangement of parts illustratedin the accompanying drawings and, while I have shown therein what is now regarded as the preferred. embodiment of this invention, I desire the same to be understood as illustrative only and not to be interpreted in a limiting sense.

In the drawings annexed hereto and forming a part hereof,

Fig. 1 represents a perspective view of my combination saw-set and saw-filer, the handles being broken away to save space;

Fig. '2 represents a plan view of the structure shown in Fig. 1 with a portion of each of the handles broken away;

Fig. 3 represents an elevation with a part broken away to expose interior relationships;

Fig. 4 represents a fragmentary plan of a portion of this structure, with the saw in section;

Fig. 5 represents an elevation of the structure shown in Fi 4;

Fig. 6 represents a perspective view of an element of this construction not shown elsewhere;

Fig. 7 represents a side elevation of the structure shown in Fig. 1, taken from the left side of that figure;

Fig. 8 represents a fragmentary vertical section showing the file-holding assembly in elevation, the same being taken in the vicinity of the saw points shown in Fig. 7;

Fig; 9 represents a perspective view of a part of file-holding assembly, a portion thereof the opposite direction from that represented in Fig. 7; and

Fig. 12 represents an inside face View of the member 9.

The saw-setting mechanism shown in this application is disclosed and claimed in my co-pending application, Serial No. 308,939, filed December 1939, now Patent No. 2,286,098, granted June 9, 1942, and is shown here merely for the sake of illustrating the connection between the saw-set and the saw-filer, there being no intention to claim in this application the sawsetter, as such.

A base element l serves as a support upon which the remainder of the structure is mounted. This base element l' is folded, as shown at 2, thus providing two parallel parts which have their edges extended into flanges 3 and 4 to furnish appropriate lateral support against tilting. As shown at 5 and 6 in Fig. 11, parts are cut away to furnish seats for the securing bolt or bolts l.' A support 8, roughly T-shaped in cross-section, has an opening therethrough through which the bolt 1 extends and in which it is secured. This support 8 may be secured in a vise or to a table or may be otherwise permanently' or removably attached to a fixed object by which the entire assembly is supported.

At the extreme rear end, the supporting memher I extends upwardly, as shown at ii in Fig. 11, to form a support for the setting unit I8. It also forms a support for the saw-guiding assembly H which clamps the saw tightly enough to prevent any retrograde motion of the saw blade during the downward motion of the sawshifting mechanism, and also clamps it suinciently tightly to prevent any chattering of the saw during the motion of filing the saw. This saw-blade clamp comprises a pair of fixed jaws l2 and I3 and a spring I8 (see Fig. 2) held together by a bolt 14, the jaw l3 having an arm l5 projecting laterally therefrom to serve as a support for the adjusting bolt It, held in place by the set nut ii. A depth gauge 28 is slotted, as shown at 21 in Fig. 5, for the reception of a guide rivet 22 which guides the gauge member in its movements toward and away from the blade 25. When the blade has been set for the proper depth of cut by the file 24, the gauge element 25 is moved toward the saw by means of the adjusting screw it until it engages the back edge of the saw so as to prevent it from moving away from the file. The flange 28a projects laterally, substantially parallel to the arm i5, to furnish an abutment against which the screw 16 may press when the gauge to is being adjusted.

A plate 25 is bent inwardly at 25c so that its upper end bears against the supporting plate I. A bolt 2! passes through an extension 25 of the plate 25 and the central part of a casting 28. The lower end of this casting rests against the shoulder formed at 25a, and the upper end thereof constitutes the jaw is and the supporting arm [5. The bolts id and 28 pass through the part l3, the former drawing the jaws l2 and I3 together, as stated above, and the latter bending the leaf spring [8 into engagement with the saw blade 23 to produce the tension mentioned above. Since the crank 30 is used only in saw setting, details of its operation will, therefore, be omitted.

A shaft 3|, rigidly secured to the crank 38, is screw-threaded at its extreme end for the reception of an adjusting nut 32 which bears against a cam member 33 which acts on a cam plate 34 for adjusting the set of the saw, as disclosed in my prior application referred to above. Of course the nut 32 must not be tightened up too tightly or the machine will fail to function properly, as the jaws of the saw setter would interfere with the movement of the saw. The function of these parts in the saw setting operation will not be discussed herein.

It has been indicated above that the upper end portion of the blade, within the machine, is prevented from moving away from the file by means of the guid 25, which is held forward by the screw it pressing against the fiange 28a of the guide 28. The lower portion of the blade 23, within the machine, is held forward by the finger 35 projecting through an opening 35 in the plate I, and a registering opening in each of the leaves of the saw setting element is. The plate 25 has an outwardly projecting flange 3? provided with an opening for the reception of the reduced end 38 of the screw 89. This projection or arm 31 serves as an abutment against which the shoulder of the screw presses when the latter is turned inwardly to draw the finger 35 against the back edge of the blade, the finger being carried by a plate 45 extending between the plates l and 25. The plate 48 is provided with a second finger 4| which extends in the opposite direction from .the finger 35. This second finger 4! is provided with a screw-threaded opening for cooperation with the screw-threaded shank of the screw 39. It is believed that the operation of this gauge element 25 will be understood from the foregoing description.

In order to lace tension upon the lower portion of the blade, as it enters the machine, a spring 32 (see Fig. '7) is secured to the support 8 and presses laterally against the same. When the blade is placed in the machine, it is slipped between this spring and the support 5, as shown in Fig. '7.

A supporting unit 44 having a sleeve 45 and a bracket arm 46 serves as a support for a crank shaft 41 by means of which the filing mechanism is operated. A screw 48 extends through an arm of the bracket 45 and engages the end of member I to hold the bracket 44 in place. A crank 45 is adjustably mounted on the shaft 41 and held in adjusted position by means of the set screw 58. The element 44 has an upwardly extending arm 5| to which is connected the laterally extending arm 52 forming a part of member 28. These two are held together by a screw or bolt 53, as shown in Figs. 2 and '7. A second screw or bolt 54 extends through the arm 52 and is held in adjusted position by means of a set nut 55. The purpose of this screw '54 will be referred to presently.

A supporting bracket 51 forms a part of the element 28 and serves to support a slide bar 58 which serves as a track or slideway for the file- .supporting assembly, shown in part in Fig. 9.

In Fig. 8, the file carriage is shown in assembled relation with its slideway and the supporting means by which the slideway is sustained. As shown in this figure, the file carriage has a spring 6| secured thereto at its mid-portion, and the spring has brackets 62 and 63 secured to its end portions, which brackets serve to support the file. The spring 61 is secured to the carriage by means of a rivet or screw 64, as shown in Fig. 8. One end of the file is inserted in an opening in the bracket 63, the other end being secured in a V-shaped notch in the bracket 52 by means of a screw 65. This screw is used to clamp the file immovably in place in the carriage.

At one of its ends, the carriage has a down wardly turned arm 66 which carries a horizontally acting cam 6'! at its lower end. A downwardly extending arm 68 at the opposite end of the carriage has a laterally extending finger 69 which cooperates with the slide bar 58. An opening it is formed in the carriage for a purpose to be explained presently. Adjusting screws II and 72 extend through the brackets 52 and 63 and have threaded engagement therewith. By adjusting these screws longitudinally, the position of the ends of the spring 61 may be adjusted to adjust the forward or cutting edge of the file parallel to the direction of movement of the file carriage when travelling in the cutting direction, in sharpening a saw.

On the remote end of the shaft 47 from the operator of the machine is a crank arm 15 which has a link 16 connected thereto by means of a bolt ll. The second end of the link it is connected to a lever 18 by means of a bolt '19. The bolts El and 19 are preferably riveted at their ends more remote from the link 16. One end of the lever 18 is connected to the support 44 by a bolt 58 which may have a set nut on the end thereof for the purpose of holding the bolt in properly adjusted position. The other end of the lever 18 has a hole therethrough for the reception of a bolt 8| provided with a large rectangular head 82, through which extends an opening 83 for the receptionof a link 84. One end of the link 84 'is bent at a substantially right angle to provide a laterally extending end 85 which is received in the opening 10, referred to above;

When the lever 18 is swung to its farthest left position .(see Fig. 3), the position of its axial line will be as shown at a. As the crank 49 is rotated, the lever swings to the right through the position 2) to the position 0. During the movement from b to c, thespring 90 is-compressed.

A yoke 86 has its ends 81 and 88 (see Fig. 3) aperturedfor the reception of the link 84. The opening in the end 3'! is screw-threaded for the reception of the screw-threaded end of the link, the yoke being normally fixed in position on the link but capable of relative adjustment with respect thereto. When the end of the link has been screwed into the threaded opening in the end 87 until the desired adjustment is secured, the nut 89 is tightened up to hold the two in relatively adjusted position. The head 82 of the bolt Si is slideable on the link 84 when the link is immovable and the lever 78 is moved toward the right at its upper end, as viewed in Fig. 3. A spring 90 surrounds the link 83 and is located between thehead 82 and the arm 88 of the yoke 86. This spring is always under some tension, since it is made long enough to need to be somewhat compressed in order to get into the slotted space.

From the foregoing it will be seen that, when the crank 49 is turned, it will cause rotation of the shaft 47, and this will, in turn, rotate the crank arm 715. This will cause an oscillating, reciprocating motion of the link it and an oscillating rotary motion of the lever 18 about its pivot 80 (see Fig. 3). This will cause reciprocation of the link 8t and the file carrier 60, to which the link is connected by the arm 68 and the end 85. It is therefore obvious that, during a complete rotation of the crank 49, the file carrier will be caused to move from any position in its complete cycle to one end or the other of its course of travel, and then return to the other end and back to the point of starting. It is therefore apparent that the cycle of operation of the file carrier coincides with the cycle of the crank. However, the file carrier does not move throughout the entire cycle of the crank for the reason that its reciprocation toward the right, as viewed in Figs. 1 and 2, is stopped by engagement of the cam 61 with a cam 9i on an arm 1a of supporting bracket 5? and its inability to yield far enough laterally to permit its movement with the crank throughout the travel of the latter. When the reciprocation of the file carriage is arrested, the lever 18 continues its motion to the right (see Fig. 3), carrying 82 with it and compressing" spring 90, as mentioned above. This insures a reserve of possible movement so that, if the machine wears, completion of the cycle of the carriage and of pawl 93 will be insured. If, after a considerable period of use, still further adjust-' ment is required, the hook 85 may be unhooked from bracket or arm 68, the nut 89 loosened somewhat to permit rotation of the link fi l, and then, after a sufficient rotation of this link about its axis, the nut 89 is again tightened up to bind the arm 8'4 between the head 82 and the nut 89. It is clear that the hole 83 is not threaded since the head 82 and the link 84 must be free to slide relatively.

There is enough of looseness between the bar 58 and the arms 61 and 69 to permit a slight rocking of the file carriage with relation to the slide bar. This is made use of in withdrawing the file from its engagement with the saw blade and in undercutting the teeth so that the forward faces of the teeth will have the proper inclination to do good cutting. The mechanism for producing this rocking will next be described.

Secured in the casting 28 is a pivot member 92, and on this member is mounted a lever 93 provided with'a finger 94. This lever tithes a flange 95 through which'extends abolt ii, surrounded by a spring 91. At one end, this spring bears against the head of the bolt and at its other end against the fiangeilE. The second end of the bolt extends through the membert'i'l (see Fig. 11) and has a nut thereon for adjustment of the spring tension on the lever Throughout most of the course of travel of the carriage til, the flange '95 bears, at its upper end, against the lower edge portion of carriage. 69, causing this carriage to rock in a counterclockwise direction, as viewed in Fig. 7, when the cam 6? is pushed away from the saw clamp l2, It. This motion of the cam .67 is caused by its engagement with cam Q! (see Fig. 10). The engagement of the rounded corner of cam til with. a like rounded corner'93 of cam 95 causes rapid Withdrawal of carriage 60 from the saw clamp l2, it. This is order to get the file 24 away from the saw teeth so that the saw can be shifted for the filing of the next tooth. As soon as the carriage fill moves to the left (see Fig. 2) far enough to clear the cam 67 from the cam M, the carriage moves to the left (see Fig. 7) to cause engagement of the file with the saw, resulting in the filing thereof as the carriage continues its movement. When the cam 61 leaves the cam 92, the carriage 68 rocks so that the forward or cutting edge of the file turns upward so as to give the upper face of the file an inclination'of approximately ten degrees (10) whereby to produce an undercut of that amount to the teeth of the saw.

At substantially the same time that the cam 67 rides along cam El, with the right hand motion of the carriage as viewed in Fig. 3, the flange 95 of lever 93 drops into the notch 99 in the under side of carriage 60 and engages cam 100 thereof (see Fig. 3'). The spring ill! forces the lever 93 to push the carriage toward the saw and hold the file in engagement with the saw'during the filing operation. However, the coaction of the cams 6i and 9! causes movement of the file away from the saw and compression of the spring 91'.

An arm M32 is pivotally mounted on and with respect to the shaft 3| and has an arm #03 projecting laterally therefrom, as shown in Figs. 1, 2, and 11. A pivot H34 supports a pawl Hi5, carrying a head I06, upon the arm 152. On the upper face of this pawl, adjacent the casting 28, is an upwardly projecting rib which fits into a notch cut in the under face of a stop N98 to hold the pawl rigidly against sidewise swinging. The stop IE8 is formed by cutting a notch in the edge of support =9, as shown at [88. Therefore, when pawl I05 is raised and its head strikes the upper edge of this notch, the pawl will be stopped and held rigidly against further movement.

Reciprocating movement of the pawl M5, in an upward direction, is caused by a bellcrank lever I ll) pivoted at l l I on member 28. The upper end portion of lever Ill] bears against the back face of carriage 60 but is not ordinarily spring-actuated in either direction. However, a spring H2, attached atits lower end to, plate 25 and at its upper end to pawl Hi5, pulls the latter downwardly, causing the head tilt to engage the arm H3 of the bellcrank and pull it downwardly, provided, of course, that the carriage Bil is not held out by the earns 67 and 9!. It will therefore be seen that, besides having the function hereinbefore described, the cams 61 and 9| have the additional function of causing the upward spacing of the saw, one tooth at a time. Of course, when the head I06 engages the upper edge of the tooth I09, the pawl I05 can move no farther, and this controls the upward movement of the arm H3 and the swinging of the bellcrank H0. This, in turn, as pointed out above, stops the traversing of the carriage and the file. The upper face of the arm H3 is curved downwardly, as shown in Fig. 7, to assist in forcing the pawl I05 toward the saw.

The screw 54, referred to above, serves as an adjustable stop to adjust the amount by which the arm H3 of lever H0 may move downwardly and the upper arm of this lever may move toward the track 58. It also regulates the amount which the head I85 may move downwardly to engage the next tooth. This varies with the number of points per inch which, in the trade, is always one greater than the number of teeth per inch. The tooth engaged by the head 106 when advancing the blade is one inch below the tooth to be filed by the file during its next filing movement. Therefore, the operator is assured that the blade will always be positioned exactly right and no tooth will ever be skipped.

While I have referred to the shaft operating means 49 as a crank and the shaft 41 as a crank shaft, it is to be understood that these terms have been used in a broad sense as meaning means for revolving the arm about an axis. A pulley mounted on the shaft 4'! would be the equivalent of the crank 49. The shaft 41 is made long enough to carry the crank, pulley, or other operating means 49 outwardly beyond the edge of the table or bench upon which the machine may be mounted.

No reel or other support for the saw is re-,

quired, the machine furnishing all the support that is needed. A noteworthy fact about this machine is that the shaft may be rotated in either direction and the operation thereof will be identically the same. Attention is called to the ease with which the file carriage may be removed from its track, simply by unhooking 85 from 68, sliding the carriage nearly to the right hand limit of its motion (see Fig. 2) and then unhooking 69 from 58. After this, the hook or arm 66 may be withdrawn from the track 58.

It will, of course, be understood that the specific description of structure set forth above may be departed from without departing from the spirit of this invention as set forth in this specification and the appended claims.

Having now described my invention, I claim:

1. In a saw sharpening mechanism, a support, a bracket thereon, a shaft mounted in said bracket, a pivot connected to said shaft, ec centrically with relation thereto, and revolving about the axis of said shaft as the shaft is rotated, a lever pivotally mounted .on said bracket, a link connecting said lever to said pivot, a reciprocatory carriage mounted for rotary oscillation in a direction transverse to the direction of reciprocation thereof, a file carried thereby, a saw blade support for holding a saw closely adjacent to said file, and a linkage connection between said lever and carriage so that rotation of the shaft will cause reciprocation of the file across the saw.

2. In a saw sharpening machine, in combination, a supporting base, a bracket clamped thereto, means secured to the base for clamping a saw blade to be sharpened, said means comprising also a carriage support, a carriage slidable longitudinally of said support, a file carried by said carriage with its longitudinal axis approximately parallel to the length of the support, said carriage being oscillatably rotatable transversely to the length of its support whereby to carry the forward edge of the file downward away from a saw tooth as the file is retracted from the saw, a rotary shaft carried by said bracket, operative means connecting the shaft and the carriage to cause reciprocation of the carriage and file along the carriage support when the shaft is rotated, cam means for shifting the carriage and file away from the saw near one end of the longitudinal motion thereof, and actuating means for the saw to shift it longitudinally during the time the file is held away from the saw.

3. In a saw sharpener, saw holding means for gripping and tightly holding a saw blade, a file carriage support extending transversely to the plane of the saw, a carriage reciprocable on said support, and a file carried thereby, said carriage and file being capable of limited oscillatory rotational motion approximately perpendicularly to the length of the carriage support.

4. A structure as defined by claim 3 having cam means for moving one end of the file carriage away from the saw blade as that end of the carriage approaches the limit of its traverse at which it is nearest to the saw.

5. A structure as defined by claim 3 in which the carriage fits the carriage support loosely enough to allow limited oscillatory motion of the carriage transversely to the length of the carriage support.

6. In a saw sharpening machine, saw clamping means for holding a saw blade to be sharpened, a file carriage support adjacent the saw clamping means and extending approximately perpendicularly thereto, a file carriage mounted on said support and slidable longitudinally thereof, said carriage resting on said support and having adjacent each end an arm to extend under the carriage support and hold the carriage in position thereon, said arms being readily un'hooked from said support for the removal of the carriage from the support.

ALF-RED WM. KNUTSON. 

